1. Field of the Invention
Systems and methods consistent with the present invention relate to a distributed file system, and more particularly, to replacing cache data in a distributed file system capable of replacing cache data by considering the degree of network instability between a server and a client.
2. Description of the Related Art
In general, a distributed file system enables data in a server to be used as if the data is in a device of a user.
In the distributed file system, the server manages data required for operating a predetermined system, and the data is accessed by a client. Also, in the distributed file system, when the client uses the data managed by the server, the client stores the data in a cache memory of the client so that whenever the same data is used, the client can use the data without a need to access the server. In this distributed file system, when an empty space does not exist any more in the cache memory of the client, replacement of the data stored in the cache memory (hereinafter referred to as “cache data”) is required.
Related art methods of replacing cache data in the distributed file system include a method of determining whether to replace the cache data based on the frequency of use of data or if the data has been recently used, and a method of determining whether to replace the cache data by examining the use sequence of data and thereby predicting data not to be used.
In a distributed file system operating in a wireless environment, a network between a server and a client may be disconnected at any time, and this situation is not considered in the conventional cache replacement methods.
That is, the distributed file system operating in an environment in which the network between the server and the client can be disconnected at any time should be able to operate without inconvenience even though the network is temporarily disconnected.